The invention relates generally to the field of digital data processing systems, and more particularly to systems and methods of determining transfer of files among, for example, disk storage devices comprising a mass storage subsystem or server to speed up access to data stored therein. In addition, the invention relates more particularly to systems and methods for predicting and evaluating the likely increase in performance that might result if files is moved from one disk storage device to another.
In enterprise data processing arrangements, such as may be used in a company, government agency or other entity, information is often stored on servers and accessed by users over, for example, a network. The information may comprise any type of information that of programs and/or data to be processed. Users, using their personal computers, workstations, or the like (generally, xe2x80x9ccomputersxe2x80x9d) will enable their computers to retrieve information to be processed, and, in addition, to.
Generally, servers store data in mass storage subsystems that typically include a number of disk storage units. Data is stored in units, such as files. In a server, a file may be stored on one disk storage unit, or alternatively portions of a file may be stored on several disk storage units. A server may service access requests from a number of users concurrently, and it will be appreciated that it will be preferable that concurrently-serviced access operations be in connection with information that is distributed across multiple disk storage units, so that they can be serviced concurrently. Otherwise stated, it is generally desirable to store information in disk storage units in such a manner that one disk drive unit not be heavily loaded, or busy servicing accesses, and while others are lightly loaded or idle. To accomplish that, it may be necessary to move, for example, frequently-accessed files from one disk storage unit, which may be relatively busy to another disk storage unit, which may be relatively idle. A problem arises, however, in determining whether a particular disk storage unit is relatively busy or idle. In addition, a problem arises in determining the likely performance increase that may be expected if a particular file is moved from one disk storage unit to another, which may be useful in determining whether a file should be moved from the relatively busy disk storage unit to the relatively idle disk storage unit. It will be appreciated that, if a file is moved from the relatively busy disk storage unit to the relatively idle disk storage unit, it may be desirable or necessary to also move one or more files from the relatively idle disk storage unit to the relatively busy disk storage unit, because of storage space limitations, so that the disk storage unit to which the file is moved does not itself become overloaded because of the move, or for other reasons that will be apparent to those skilled in the art. In any case, if the performance increase is predicted to be relatively small, a system administrator, for example, may determine that the file or files should not be moved. On the other hand, if the performance increase is predicted to be sufficiently large, the system administrator may deem it appropriate to move the file or files.
The invention provides a new and improved systems and methods of determining transfer of data among, for example, disk storage units comprising a mass storage subsystem or server to speed up access to data stored therein. In addition, the invention provides a new and improved system and method for predicting and evaluating the likely increase in performance that might result if data is moved from one disk storage device to another.
In brief summary, the invention provides, in one aspect, a busy disk evaluation system comprising a busy disk evaluation module and a control module. The busy disk evaluation module is configured to perform a busy disk evaluation operation in which it processes access request statistics relating to access requests directed to a server, the server including a plurality of disk storage units, respective access requests requesting access to respective ones of the disk storage units, to identify which, if any of the disk storage units is busy. The busy disk evaluation module is configured to determine whether a disk storage unit is busy in relation to a ratio between the number of access requests requesting access to the disk storage unit per unit time exceeds a selected access request per unit time threshold in relation to a total number of access requests and a selected ratio threshold. The control module is configured to control the busy disk evaluation module. In that operation, the control module is configured to provide the busy disk evaluation module with the selected ratio threshold.
In another aspect, the invention provides a busy disk evaluation module comprising an access request statistics processor module, a ratio determination module and a comparator. The access request statistics processor module is configured to process access request statistics relating to access requests directed to a server, the server including a plurality of disk storage units, respective access requests requesting access to respective ones of the disk storage units, to identify, for each disk storage unit,
i. an access request high rate value corresponding to the number of access requests requesting access to the disk storage unit per unit time; and
ii. an access request total value corresponding to the total number of access requests.
The ratio determination module is configured to determine, for each disk storage unit, a ratio value corresponding to the ratio between the access request high rate value and the access request total value for the respective disk storage unit. The comparator is configured to determine, for each disk storage unit, whether the ratio value determined by the ratio determination module is in selected relation to a selected ratio threshold and, if so, determine that the respective disk storage unit is busy.